Roasting-kiln.



1 No. 878,704. PATENTED FEB. 11, 1908.

'J. ZELL'WEGER. ROASTING KILN APPLIGATION FILED 111311.22, 1907.

.IOHN ZELLWEGER, OF ST. LOUIS, MISSOURI.

ROASTING-KILN.

Specification of Letters Patent.

Patented Feb. 11, 1908.

Application filed April 22| 1907. Serial No. 369.630.

T all whom it may concern:

Be it known that I, JOHN ZELLWEGER, a citizen of the United States, residing at St. Louis, Missouri, have invented a certain new and useful Improvement in Roasting- Kilns, of which the following is a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to thev accom anying drawings, forming part of this speci lcation, in which- Figure 1 is a cross sectional view of a kiln constructed in accordance with my invention, the left hand half of this figure being taken on the section line 1-1 of Fig. 4 and the right hand half being taken on the section line la--la of Fig. 4; Fig. 2 is a cross sectional view, the le t hand half of which is taken on the section line 2-2 of Fig. 4 and the right hand half of which is taken on the section line 2am-2a of Fig. 5; Fig. 3 is a cross sectional view taken on the line 33 of Fig.` 4; Fig. 4 is a vertical longitudinal sec tional view taken through the center of the kiln; Fig. 5 is a horizontal sectional view taken on approximately the line 55 of Fig. 4; and Fig. 6 is a detail view illustrating a portion of the stirrer.

This invention relates to roasting kilns of that type in which the gases emanating from the ore do not mingle with the re gases by which the ore is heated.

One objectv of my invention is to provide means for utilizing the maximum of the heat in the fire gases.

Another object is to produce and maintain the required temperature along the entire length of the hearth of the kiln.

Another object is to provide free access of air to the material which is being heated. And still another object of my invention is to provide means for cooling the stirring apparatus which is used for turning over the material which is being heated.

The roasting kilns are either open kilns,

in which the gases emanating from theore mingle with the fire gases, or they are closed kilns, known as muffle furnaces, in which those two kinds of gases do not mingle.

' The following description has reference to kilns which are constructed to supply heat tothe ore during its roasting process:

In the open kilns the ore is heated, either from above by radiation of heat from a flame and from the roof of the kiln chamber, or it n is heated from below by conduction of heat through the hearth from fire gases in flues or chambers underneath the hearth, or it is heated in both ways. In the closed kilns the Vore always receives heat from the outside by conduction through the chamber or muflle walls, preferably, through the hearth. The most economical heating of ores can be effected in closed kilns from below, Vbecause in this case the heat reaches the ore before it can escape through the kiln walls and because the quantity of air passing through the kiln chamber can be limited to the amount necessary for the roasting process and there is then no excess of air to carry away heat.

In the under fired closed kilns or muffle furnaces used heretofore, a considerable quantity of heat is lost downwardly into the ground and sidewise through the ue walls to the outside. For the purpose of preventingthe loss of heat downwardly I isolate the fire flues from the ground by air spaces underneath them and by heating in these flues the air which is necessary for the combustion of the fuel used in heating the hearth. The loss of heat from the fire ilues sidewise to the outside is prevented in a great measure by air spaces in the walls of the outside iiues and also air spaces between said walls and the side walls of the kiln chamber.

In the muie kilns with bottom heat, as used heretofore, the fire-places are located only at one end of the hearth, which causes the temperature of the hearth to be high near the fire-place and low at a distance from the fire-place and, as a consequence, prevents a high output. This defect I remedy by roducing heat underneath the hearth at di erent places along its longitudinal extent, and thereby replacing the heat which has been given up by the fire gases to the hearth. In this way I keep the temperature of the hearth up to a high degree and increase theA capacity of the kiln. The fuel for such intermediate under fire is preferably gas or oil. In the muflle kilns used heretofore, the sulfurous gases, owing to their reat specific gravity, float near the surface of the ore and thereby prevent free access of the lair t0 the ore. This defect I remedy by blowing air across the hearth, thereby clearing away the heavy sulfur gases and bringing fresh air in contact with the ore.

Referring to the drawings which illustrate the preferred form of my invention, 1 designates the hearth on which the ore is placed, said hearth being supported by a plurality of parallel walls 2 which extend longitudinally of the kiln. The spaces between these walls are divided by horizontally disposed partitions Sso as .to produce lire flues 4 located directly beneath the hearth and air ducts or flues 5 located beneath the fire flues.

The ire iiues extend throughout the entire length of the hearth, and at several points along the length of the hearth are cross ilues or conduits 6 located beneath the fire fiues and communicating therewith by means of ports 7, as shown in Fig. 4, fuel being supplied to these cross ilues by means of conduits 7a leading from gas producers 8, as shown in Figs. 2 and 5. At the feed end of the kiln is a cross flue 6aL that communicates with the fire flues and leads to a chimney 9. Adjacent these cross flues 6 and 6a are open-ender'l cross tunnels 10 which communicate with the air ducts or flues 5, the rear ends of said air fiues communicating with the lire flues by means of ports 1l so as to supply said fire flues with the air that is required to produce combustion of the fuel, said air being heated as it passes through said air ducts. The Walls 2' of the two outside flues are located some distance inwardly from the side walls 12 of the kiln so. that air spaces are produced 0n the sides of the outside fire iiues, these spaces constituting the wheel pits hereinafter described. Preferably, the walls 2a are provided with air iiues 5a that communicate with the cross tunnels 10, ports 30 leading laterally from said fines so as to introduce air into the kiln chamber laterally above the ore on the hearth, said air becoming heated as it passes through said fiues 5a so that it is introduced above the ore in a heated condition. These flues 5EL not only serve as a means for introducing heated air laterally above the ore on the hearth but they also serve tov isolate the outside iire iiues and thus prevent the heat from escaping laterally fromsaidiiues.

From the foregoing it will be seen that the loss of heat downwardly from the lire flues is prevented by the air ducts 5 which isolate the iire flues from the ground, the loss of heat from the fire flues sidewise to the out- Sde being prevented in a great measure by the air spaces between the outside flues and the side walls of the kiln and the air flues in the walls of the outside fire flues.

In order that there may be a free access of air to the ore on the hearth, I have provided means for introducing blasts of air through the side Walls of the kiln across the hearth so as to Clear away the heavy sulfur gases which collect over' the ore, this being accomplished by a plurality of nozzles 14 connecting with supply conduits 15 and projecting through the side walls of the kiln, as shown in Figs. 1 and 2, the roof 12a of the kiln being provided with an opening 16 through which the sulfur gases escape, as shown in Fig. 4. While it is preferable to provide nozzles 14 or similar devices for introducing blasts of air across the hearth, it is not absolutely necessary to the successful operation of my kiln that such devices be used, for the air that is introduced laterally above the ore by the air flues 5a also serves to drive off the heavy sulfur gases that collect over the ore. If desired, these flues can connect with a source of air under pressure so as to produce lateral blasts of air over the ore, instead of communicating with the open-ended cross tunnels 10, as herein shown.

The ore or material that is to be roasted is introduced into a hopper 17 at the feed end of the kiln, as shown in Fig. 4, and said material is fed onto the hearth 1 and also turned over from time to time by means of a stirrer 1S provided with wheels 19 that travel on tracks 20 in the wheel pits, as shown in Figs. 1 and 2, said stirrer being of substantially the same construction as that shown in my` prior patent No. 627,609, dated June 27, 1899, and comprising a rotatable member provided with a plurality of blades.

In Figs. 1, 3 and 4 I have only shown the stirrer diagrammatically as Fig. 6 illustrates the particular construction of the stirrer. It is immaterial, however, so far as my present invention is concerned what kind of a stirrer is used so long as it will operate to turn over the material on the hearth. In order that this stirrer may be cooled off after it has passed through the kiln I have provided cooling chambers 21 at each end of the kiln chamber. These cooling chambers are preferably formed of metal and are substantially I shape in cross section, as shown in Fig. 3, said chambers being provided. at their outer ends with doors 22 so that the kiln chamber is closed at both ends. An air chamber 23 extends over each of the cooling chambers and connects with a chimney 24 that creates a draft and thus causes a current of cold air to pass continually through the air chamber 23 to keep the cooling chamber 21 at a low temperature.

At the rear end of the kiln is a pit 25 into which the roasted ore is dumped and the bottom of said pit is preferably provided with doors that may be opened to discharge the contents of the pit into cars or other suitable conveyances. A chute 26 leads from the floor of the cooling chamber at the feed end -of the kiln, and at the lower end of said chute is a trough 27, the ore that the stirrer carries into the cooling chamber dropping down into said trough and being thereafter conveyed by some suitable means back to the hopper.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A roasting kiln provided with a hearth, a heating chamber located beneath said and supported by a plurality of walls that hearth, and means for returning the heat! which escapes downwardly and laterally from said chamber back to the chamber substantially as described.

2. A roasting kiln provided with a hearth, a heating' chamber located directly beneath the hearth, and an air chamber covering they bottom of said heating chamber; substantially as described.

8. A roasting kiln provided with a hearth, iire flues located underneath said hearth, and air flues or ducts surrounding the bottom and sides of said lire flues; substantially as described.

4. A roasting kiln provided with a hearth, and means for creating heat at several points underneath the length of said hearth; substantially as described.

5. A roasting kiln comprising a hearth, heat ues located underneath said hearth and extending longitudinally thereof, means for supplying said flues with heat, and air ducts surrounding said flues; substantially as described.

6. A roasting kiln comprising a hearth, heat lues located underneath said hearth and extending longitudinally thereof, a plurality of cross conduits provided with ports which establish communication with the heat flues, means for sup lying air tosaid heat ilues to produce com ustion of the fuel; substantially as described.

7. A roasting kiln comprising a hearth, heat 'lues located underneath said hearth and extending longitudinally thereof, means for supplying fuel to said heat flues, air ducts arranged beneath the heat flues and in communication with said flues to supply air thereto to produce combustion of thefuel, and a chimney communicating with said heat flues; substantially as described.

8. A roasting kiln. comprising a hearth, fire fiues located beneath said hearth and extending longitudinally thereof, a plurality of cross flues or conduits having ducts which lead to said fire flues, means for conducting fuel to said cross fiues, air ducts incasing the bottoms of said lire ues and communicating with the interior thereof at the points where the heat is created, and a chimney with which all of said fire flues communicate substantially as described.

9. A roasting kiln` comprising a kiln chamber, a hearth located inside of said chamber extend longitudinally of the kiln, horizontally disposed partitions which divide the spaces between lsaid walls into a series of heat ilues located directly beneath the hearth, and a series of air ducts located underneath the heat flues, the walls of the outermost heat ilues being located some distance inwardly from the side walls of the kiln chamber so as to provide air spaces, means for supplying fuel to said heat fiues at several points throughout the length of the hearth, and means for establishing communication between the air ducts and the heat iiues; substantially as described.

10. A roasting kiln comprising a kiln chamber, a hearth for supporting the'ore to be heated, means for creating heat beneath said hearth, and means for introducing blasts of air intoV said kiln chamber to drive off the heavy sulfur gases which collect over the ore; substantially as described.

11.` A kiln for roasting ore, comprising a kiln chamber, a hearth located inside of said chamber, means for creating heat underneath said hearth, and means for introducing blasts of air through the side walls of the kiln chamber to dispel the heavy sulfur gases `which collect over the ore; substantially as described.

12. A kiln for roasting ore, comprising a kiln chamber, a hearth arranged inside of said chamber, heat flues located beneath said hearth, a plurality of devices projecting through the side walls of the kiln chamber for introducing blasts of air into the interior thereof and over said hearth, and means for supplyin air to said devices; substantially as described.

1 3. A roasting kiln provided with a hearth,

cooling chambers at the opposite ends of said hearth, means for keeping said cooling chambers at a low temperature, and a stirrer adapted to travel over the hearth to turn and agitate the material thereon and thereafter come to rest in the cooling chamber to enable it to cool off substantially as described.

14. A roasting kiln comprising a kiln chamber, a hearth arranged inside of said chamber, a stirrer adapted to travel over said hearth to agitate and turn the material thereon, cooling chambers located at the opposite ends-of said kiln chamber and having their walls constructed of metal, air chambers extending over said cooling chambers, and means for creating a draft of air through said air chambers; substantially as described.

1 5. A roasting kiln comprising a kiln chamber, a hearth located inside of said chamber for supporting the material to be roasted, a stirrer adapted to travel over said hearth for turning and agitating the material thereon, metallic cooling chambers at the opposite ends of said kiln chamber to receive the stirrer, and means for creating a current of air over said cooling chambers to keep them at low temperature; substantially` as described.

16. A roasting kiln comprising a kiln chamber, a hearth located inside of said chamber for supporting the material to be roasted, a stirrer adapted to travel over said hearth for turning and agitating the material thereon, cooling chambers at the opposite ends of said kiln chamber to receive the stirrer, and

means located underneath the cooling chaml the material on the hearth; substantially as ber at the feed end of the kiln to receive the described. material that the stirrer carries into said I In testimony whereof I hereunto aiiX my chamber; substantially as described. signaturei in the presence of two Witnesses, 5 17. Aroasting kiln provided with a hearth, this twentieth day of April 1907.

a plurality of lire flues located underneath the JOHN ZELLWEGER hearth, air lues coverin the lower sides of said fire flues, 'and air ues formed in the Vitnesses:

walls of the outside lire lues and having lat- WELLS L. CHURCH, 10 eral ports which introduce air laterally above GEORGE BAKEWELL. 

